1. Field of the Invention
A mechanical drive mechanism used to transfer driving force between at least a first member and a second member in either of two opposite, reverse directions with a minimal amount of lost motion and further positionable in a locked neutral position. Either the first or second member can be utilized as the input or output member and the mechanism can be structured shiftable between the various positive drive or neutral positions.
2. Description of the Prior Art
The prior art is replete with mechanical drive assemblies and/or clutch mechanisms specifically designed to transfer driving force from an input member to an output member. Typically, the goal for which such mechanisms are designed is to operate in a most efficient manner by incorporating a minimal amount of lost motion and further wherein certain ones of the mechanisms are capable of being operated in reverse, drive directions. One specific field of application commonly incorporating such drive mechanisms is a ratchet assembly or the like utilized in hand tools. Such ratchet assembly or mechanism is disclosed in the U.S. patent to Dane, U.S. Pat. No. 3,534,836 directed to a ratcheting device comprising a housing, a socket member rotatably mounted therein and a number of paired sprag members pivotally mounted in spaced notches on the socket member. A control structure is mounted on the housing for rotation in either direction to engage and pivot a desired one of each sprag pair away from the housing. The other sprag of each pair will permit rotation of the housing relative to the socket member in the direction of the pivoted sprag but will jam if the housing is rotated in the other rotation thereby providing a ratcheting action between the housing and the socket.
The U.S. patent to Sederquist, U.S. Pat. No. 3,599,767 discloses a reversible sprag clutch having a plurality of sprags disposed between spaced, opposed circular surfaces of two concentric members forming races for convex-convex contact wherein each of the sprags has two distinct inner cam surfaces, one of which can be employed to prevent relative clockwise rotation between the concentric members and the other of which can be employed to prevent counterclockwise rotation of the concentric members. The structure is so designed that the clutch transmitting torque in one direction will allow unrestricted rotation in the opposite direction depending upon which of the inner cam surfaces is cooperating with the inner race. The utilization of a selector ring is provided to bias the individual sprags to selectively reverse the direction of torque transmission and allow "free-wheeling" in the opposite direction.
The patent to Titt, U.S. Pat. No. 3,363,733; discloses an over running clutch having inner and outer rotary members which define between themselves an annular space in which a plurality of motion transmitting bodies are situated for tilting movement between clamped positions where these bodies are respectively clamped between clutch members for transmitting rotary motion therebetween and unclamped positions where the bodies are respectively in positions permitting free rotary movement of one of the clutch members relative to the other.
While the structures disclosed in the above set forth patents are assumed to be operable for their intended functions, each may be considered to be somewhat over complicated by utilizing a plurality of cooperative moving parts, the inability to assume a readily reversed, position drive direction of travel and force transmission as well as the inability to selectively assume a locked neutral position without significant modification of the structural features thereof.